Siloxane resin coating

ABSTRACT

A siloxane resin having the formula: (HSiO 3/2 ) a (RSiO 3/2 ) b (SiO 4/2 ) c  where R is Z, Z(CH 2 ) n  or ZO(CH 2 ) n  where Z is a phenyl or substituted phenyl group; n has a value of 1 to 6, a has value of 0.01 to 0.7, b has a value of 0.05 to 0.7, c has a value of 0.1 to 0.9 and a+b+c≈1. The siloxane resins are useful in anti-reflective coating compositions.

This invention relates to siloxane resin useful in antireflectivecoating compositions for use in fabricating semiconductor devices. Thesiloxane resins have the formula(HSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c) where R is Z, Z(CH₂)_(n)or ZO(CH₂)_(n) where Z is a phenyl or substituted phenyl group; n has avalue of 1 to 6, a has value of 0.01 to 0.7, b has a value of 0.05 to0.7, c has a value of 0.1 to 0.9 and a+b+c≈1.

Photolithography is a known technique in the art of semiconductorfabrication. In a typical photolithography process, a semiconductorwafer is coated with a barrier layer, i.e. an anti-reflective coating(ARC) layer. Thereafter, a photoresist layer is coated on the ARC layer.The photoresist/ARC/semiconductor wafer is then brought into proximityto a source of electromagnetic radiation, typically ultraviolet light(UV) having a wavelength from about 150 nm to about 300 nm, and a maskis interposed between the electromagnetic radiation source and thephotoresist/ARC/semiconductor wafer. The mask is generally opaque to thewavelength of electromagnetic radiation used, but has transparentregions defining a desired pattern to be imparted to the photoresistlayer.

When the source emits electromagnetic radiation, the mask allowsexposure of electromagnetic radiation to particular and user-definedregions of the photoresist layer. Both positive photoresists andnegative photoresists are known. In a positive photoresist, the regionsof photoresist exposed to UV, as well as the regions of the ARC layerthereunder, will be sacrificed during subsequent developing steps. In anegative photoresist, the regions of photoresist that are not exposed toUV, as well as the regions of the ARC layer thereunder, will besacrificed during subsequent developing steps.

Regardless of the details of the photolithography process, an ARC layerdesirably has several properties. One property is a relatively highextinction coefficient, i.e., a relatively strong ability to absorb thewavelength of electromagnetic radiation used, rather than reflect theelectromagnetic radiation up to the photoresist layer. A second propertyis a relatively low resistance to liquid stripping agents, such asdiluted hydrofluoric acid, in order to be more quickly and easilyremoved after photolithography and minimize the extent of damage by astripping agent to the low-k dielectric material on a wafer.

This invention relates to a siloxane resin having the formula(HSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c) where R is Z, Z(CH₂)_(n)or ZO(CH₂)_(n) where Z is a phenyl or substituted phenyl group; n has avalue of 1 to 6, a has value of 0.01 to 0.7, b has a value of 0.05 to0.7, c has a value of 0.1 to 0.9 and a+b+c≈1. The siloxane resins areuseful in anti-reflective coating compositions.

This invention also relates to a method for preparing the siloxaneresin, wherein the method comprises reacting HSiX₃, RSiX₃, SiX₄ andwater in an organic solvent, where X is a hydrolyzable groupindependently selected from Cl, Br, CH₃CO₂—, an alkoxy group having 1 to6 carbon atoms, or other hydrolyzable groups.

This invention relates to a method of preparing an anti-reflectivecoating on a substrate, comprising coating a composition onto asubstrate to form a coated substrate, wherein the composition comprisesa siloxane resin having the formula(HSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c) where R is Z, Z(CH₂)_(n)or ZO(CH₂)_(n) where Z is a phenyl or substituted phenyl group; n has avalue of 1 to 6, a has value of 0.01 to 0.7, b has a value of 0.05 to0.7, c has a value of 0.1 to 0.9 and a+b+c≈1; and curing the coatedsubstrate, to form the anti-reflective coating on the substrate.

This invention relates to a semiconductor wafer, prepared according tothe above method of preparing an anti-reflective coating on a substrate.

The siloxane resins of the present invention provide ARC layers havingrelatively high extinction coefficients for UV having wavelengths fromabout 150 nm to about 220 nm, and a relatively low resistance to liquidstripping agents such as a solution containing fluoride salt, (a highwet etch rate).

The siloxane resin is comprised of HSiO_(3/2), SiO_(4/2) and RSiO_(3/2)units. A proportion of the units in the resin comprise one or moresilanol or alkoxy (Si—OH or Si—OR′ when the solvent is R′OH such as1-methoxy-2-propanol) moieties. Typically 10-40% of the units in theresin contain silanols or alkoxy moieties.

In the siloxane resin a has a value of 0.01 to 0.7, alternatively 0.2 to0.5, b has a value of 0.05 to 0.7, alternatively 0.15 to 0.35, c has avalue of 0.1 to 0.9, alternatively 0.25 to 0.6 with the provision thata+b+c is approximately equal to 1. One skilled in the art will recognizethat other units, (e.g. M and D units) may be present in the resin dueto impurities in the starting materials or rearrangement during theproduction of the resin. The siloxane resins typically have aweight-average molecular weight of 2000 to 200000, alternatively 3000 to15000.

In the siloxane resin, R is selected from Z, Z(CH₂)_(n) or ZO(CH₂)_(n)where Z is a phenyl or substituted phenyl group. Substituted phenylgroups contain at least one HO—, MeO—, Me-, Et- Cl— and/or othersubstituents. R may be exemplified by, but not limited to,(2-HO)PhCH₂CH₂CH₂—, PhCH₂CH₂—, and Ph where Ph represents a phenylgroup.

This invention relates to a method for preparing a siloxane resinwherein the method comprises reacting water, HSiX₃, RSiX₃ and SiX₄ in anorganic solvent, where X is a hydrolyzable group independently selectedfrom Cl, Br, CH₃CO₂—, an alkoxy group having 1 to 6 carbon atoms, orother hydrolyzable groups. The silanes useful herein can be exemplifiedby, but not limited to, HSi(OEt)₃, HSiCl₃, Si(OEt)₄, SiCl₄,(2-HO)C₆H₄CH₂CH₂CH₂Si(OEt)₃, PhCH₂CH₂SiCl₃, and PhSiCl₃ where Etrepresents an ethyl group and Ph represents a phenyl group.

The amount of silane reactants (HSiX₃, RSiX₃ and SiX₄) in the reactionmixture is such that there is typically 1 to 70 mole %, alternatively 20to 50 mole % HSiX₃; 5 to 70 mole %, alternatively 15 to 35 mole % RSiX₃,and 10 to 90 mole %, alternatively 25 to 60 mole % SiX₄ with theprovision that the amount of HSiX₃, RSiX₃ and SiX₄ is approximately 100mole % based on the total moles of HSiX₃, RSiX₃ and SiX₄.

The amount of water in the reaction is typically in the range of 0.5 to2 moles water per mole of X groups in the silane reactants,alternatively 0.5 to 1.5 moles per mole of X groups in the silanereactants.

It is preferred to carry out the reaction for a time sufficient foressentially all of the X groups to undergo hydrolysis reactions. Thereaction time will depend upon the silane reactants and the reactiontemperature. Typically the reaction time is from minutes to hours,alternatively 10 minutes to 1 hour. The temperature at which thereaction is carried out is typically in the range of 25° C. up to thereflux temperature of the reaction mixture. Typically the reaction iscarried out by heating under reflux for 10 minutes to 1 hour.

The reaction step comprises both hydrolyzing and condensing the silanecomponents. To facilitate the completion of the reaction a catalyst maybe used. The catalyst can be a base or an acid such as a mineral acid.Useful mineral acids include, but are not limited to, HCl, HF, HBr,HNO₃, and H₂SO₄, among others, typically HCl. The benefit of HCl orother volatile acids is that a volatile acid can be easily removed fromthe composition by stripping after the reaction is completed. The amountof catalyst may depend on its nature. The amount of catalyst istypically 0.05 wt % to 1 wt % based on the total weight of the reactionmixture.

Generally, the silane reactants are either not soluble in water orsparingly soluble in water. In light of this, the reaction is carriedout in an organic solvent. The organic solvent is present in any amountsufficient to dissolve the silane reactants. Typically the organicsolvent is present from 1 to 99 weight percent, alternatively 70 toabout 99 wt % based on the total weight of the reaction mixture.Suitable organic solvents include, but are not limited to, THF, ethanol,propanol, 1-methoxy-2-propanol, 2-ethoxyethanol, MIBK, propylene methylether acetate and cyclohexanone.

In the process for making the siloxane resin, after the reaction iscomplete, volatiles may be removed from the siloxane resin solutionunder reduced pressure. Such volatiles include alcohol by-products,excess water, catalyst and solvents. Methods for removing volatiles areknown in the art and include, for example, distillation or strippingunder reduced pressure.

To increase the molecular weight of the siloxane resin and/or to improvethe storage stability of the siloxane resin the reaction may be carriedout for an extended period of time with heating from 40° C. up to thereflux temperature of the solvent (“bodying step”). The bodying step maybe carried out subsequent to the reaction step or as part of thereaction step. Preferably, the bodying step is carried out for a periodof time in the range of 10 minutes to 6 hours, more preferably 20minutes to 3 hours.

This invention also relates to a anti-reflective coating compositioncomprising (A) a siloxane resin having the formula(HSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c) where R is Z, Z(CH₂)_(n)or ZO(CH₂)_(n) where Z is a phenyl or substituted phenyl group; n has avalue of 1 to 6, a has value of 0.01 to 0.7, b has a value of 0.05 to0.7, c has a value of 0.1 to 0.9 and a+b+c≈1; and

(B) a solvent.

Useful solvents include, but are not limited to, 1-methoxy-2-propanol,and propylene methyl ether acetate and cyclohexanone, among others. Theanti-reflective coating composition typically comprises from about 10%to about 99.9 wt % solvent based on the total weight of the composition,alternatively 80 to 95 wt %.

The anti-reflective coating composition can further comprise a curecatalyst. Suitable cure catalysts include inorganic acids, photo acidgenerators and thermal acid generators. Cure catalysts may beexemplified by, but not limited to sulfuric acid (H₂SO₄),(4-Methylthiophenyl)methyl phenyl sulfonium triflate and 2-Naphthyldiphenylsulfonium triflate. Typically a cure catalyst is present in anamount of up to 1000 ppm, alternatively 500 ppm.

The anti-reflective coating composition can further comprise additionalcomponents useful in coating applications or in other applications forwhich the composition can be used.

In one embodiment, the composition further comprises water. Thecomposition can comprise from about 0% to about 5% water by weight.

This invention relates to a method of preparing an anti-reflectivecoating on a substrate, comprising:

(I) applying an anti-reflective coating composition onto a substrate toform a coated substrate, wherein the anti-reflective coating compositioncomprises

(A) a siloxane resin having the formula siloxane resin having theformula (HSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c) where R is Z,Z(CH₂)_(n) or ZO(CH₂)_(n) where Z is a phenyl or substituted phenylgroup; n has a value of 1 to 6, a has value of 0.01 to 0.7, b has avalue of 0.05 to 0.7, c has a value of 0.1 to 0.9 and a+b+c≈1; and

(B) a solvent and

(II) curing the coated substrate, to form the anti-reflective coating onthe substrate.

The substrate can be any material. Typically the substrate is asemiconductor device, such as silicon-based devices and galliumarsenide-based devices intended for use in the manufacture of asemiconductor component. Typically, the device comprises at least onesemiconductive layer and a plurality of other layers comprising variousconductive, semiconductive, or insulating materials.

Specific methods for application of the anti-reflective coatingcomposition to the substrate include, but are not limited to,spin-coating, dip-coating, spay-coating, flow-coating, screen-printingand others. The preferred method for application is spin coating.Typically, coating involves spinning the substrate, such as at about2000 RPM, and adding the anti-reflective coating composition to thesurface of the spinning substrate.

The coated substrate is cured to form the anti-reflective coating on thesubstrate. Curing generally comprises heating the coated substrate to asufficient temperature for a sufficient duration to lead to curing. Forexample, the coated substrate can be heated at 80° C. to 450° C. for 0.1to 60 minutes, alternatively 150° C. to 225° C. for of 0.5 to 2 minutes.Any method of heating may be used during the curing step. For example,the coated substrate may be placed in a quartz tube furnace, convectionoven or allowed to stand on hot plates.

To protect the siloxane resin of the coated composition from reactionswith oxygen or carbon during curing, the curing step can be performedunder an inert atmosphere. Inert atmospheres useful herein include, butare not limited to nitrogen and argon. By “inert” it is meant that theenvironment contain less than 50 ppm and preferably less than 10 ppm ofoxygen. The pressure at which the curing and removal steps are carriedout is not critical. The curing step is typically carried out atatmospheric pressure however, sub or super atmospheric pressures maywork also.

In the instant invention the siloxane resins can be used to producecoatings that have unique coating, surface, optical and wet etchingproperties. They may be used to form thin films by spin-coating, arecrosslinked and become solvent-resistant after a soft baking, have watercontact angle between 55 and 75 degrees, absorbs light at a wavelengthbelow 220 nm, and can be easily removed by wet etching.

Once cured, the substrate comprising the anti-reflective coating can beused in further substrate processing steps, such as photolithography.

The following examples are included to demonstrate preferred embodimentsof the invention. It should be appreciated by those of skill in the artthat the techniques disclosed in the examples which follow representtechniques discovered by the inventor to function well in the practiceof the invention, and thus can be considered to constitute preferredmodes for its practice. However, those of skill in the art should, inlight of the present disclosure, appreciate that many changes can bemade in the specific embodiments which are disclosed and still obtain alike or similar result without departing from the spirit and scope ofthe invention.

In the following examples the film thickness (Th) was tested by using aWoollen M-2000D Ellipsometer. Film thickness reduced by PGMEA rinse(ΔTh) was tested by rinsing the film with propylene methyl etheracetate, baking the rinsed film at 180° C. for 20 seconds on a hotplate,and testing final film thickness. Water contact angle (WCA) on the filmsurface was tested by using VCA 2000 Video Contact Angle System. Opticalextinction coefficient (k) and refractive index (n) at 193 nm weretested by using a Woollen VUV-VASE VU303 Ellipsometer. Wet etch rate wastested by etching the film with Ashland NE-89 stripper at roomtemperature for 1 minutes with gentle ultrasonic agitation.

EXAMPLE 1

A siloxane resin composition,(HSiO_(3/2))_(0.35)(RSiO_(3/2))_(0.3)(SiO_(4/2))_(0.35) withR=2-HO_C₆H₄—CH₂CH₂CH₂—, was prepared by combining (A) 100 weight partsof 1-methoxy-2-propanol, (B) 2.65 weight parts of triethoxysilane, (C)3.36 weight parts of tetraethoxysilane, (D) 4.12 weight parts ofRSi(OEt)₃ and (E) 3.74 weight parts of 8.4 wt % HCl/H₂O mixture. Theresulting solution was heated under reflux for 20 minutes and strippedin reduced pressure until 60.2 weight parts of solution remained. A 1%H₂SO₄ aqueous solution of 0.65 weight parts and water of 2.5 weightparts were added, and the solution was heated under reflux for 20minutes. The final product is a light yellow solution.

The siloxane resin composition sample was filtered through an 0.2 umfilter, spin-coated on Si wafers at 2000 RPM, baked at 200° C. for 1minute on a hotplate to yield clear films. The results are summarized inTable 1.

Example 1 demonstrated that siloxane resin composition(HSiO_(3/2))_(0.35)(RSiO_(3/2))_(0.3)(SiO_(4/2))_(0.35) withR=2-HO_C₆H₄—CH₂CH₂CH₂—, can lead to thin films that are resistant toPGMEA rinse, have a water contact angle between 55 and 75 degrees,strongly absorbs 193 nm light, and can be completely removed with acommercial stripper, Ashland NE-89.

TABLE 1 Thin film properties of sample Example 1. Example Th, Å ΔTh, ÅWCA, ° k n Etch rate Å/min 1 2100 6 63 0.47 1.55 >2100

EXAMPLES 2 AND 3

Siloxane resin compositions,(HSiO_(3/2))_(0.49)(PhCH₂CH₂SiO_(3/2))_(0.16)(SiO_(4/2))_(0.35) (Example2) and (HSiO_(3/2))_(0.4)(PhSiO_(3/2))_(0.25)(SiO_(4/2))_(0.35) (Example3) were prepared by combining in a glass container cooled with anice-water bath components (A) 1-methoxy-2-propanol, (B) trichlorosilane,(C) tetrachlorosilane, (D) PhCH₂CH₂SiCl₃ or PhSiCl₃ and (E) wateraccording to Table 2. The resulting solutions were heated under refluxfor 20 minutes and stripped in reduced pressure until 50% of the totalweight remained. Water in an amount of 1.5% of total original weight wasadded and 1-methoxy-2-propanol was added until the total weights wereidentical to the original total weights. The final products were clearsolutions.

Thin films were processed from samples 2 and 3 and characterized usingthe same procedures discussed in Example 1 except that the sampleExample 3 was spin-coated at 2600 RPM. The results were summarized inTable 3.

Examples 2 and 3 demonstrated that siloxane resin compositions,(HSiO_(3/2))_(0.49)(PhCH₂CH₂SiO_(3/2))_(0.16)(SiO_(4/2))_(0.35) and(HSiO_(3/2))_(0.4)(PhSiO_(3/2))_(0.25)(SiO_(4/2))_(0.35) can lead tothin films that are resistant to PGMEA rinse, have a water contact anglebetween 55 and 75 degrees, strongly absorbs 193 nm light, and can becompletely removed with a commercial stripper, Ashland NE-89.

TABLE 2 Preparation of samples Example 2 and Example 3. Wt. Parts Wt.Parts Wt. Parts Wt. Parts Wt. Parts Example (A) (B) (C) (D) (E) 2 1006.61 5.97 3.94 6.66 3 100 6.28 6.89 6.13 7.69

TABLE 3 Thin film properties of samples Example 2 and Example 3. ExampleTh, Å ΔTh, Å WCA, ° k n Etch rate Å/min 2 2255 1 68 0.42 1.65 >2255 32184 5 69.5 0.49 1.78 >2184

COMPARATIVE EXAMPLES 4 AND 5

Siloxane resin compositions(HSiO_(3/2))_(0.84)(PhCH₂CH₂SiO_(3/2))_(0.16) (Comp. Example 4) and(HSiO_(3/2))_(0.75)(PhSiO_(3/2))_(0.25) (Comp. Example 5) were preparedby using the same procedures discussed in Examples 2 and 3 except thatthe weight parts for the components were different as shown in Table 4.The final products were both hazy solutions that could not be filteredthrough 0.2 um filter. Therefore neither of the compositions can be usedas a coating composition.

TABLE 4 Preparation of samples Comparative Examples 4 and 5. Wt. PartsWt. Parts Wt. Parts Wt. Parts Wt. Parts Example (A) (B) (C) (D) (E) C4100 12.23 0 4.24 6.42 C5 100 12.65 0 6.59 7.39

Examples 2 and 3 and Comparative Examples 4 and 5 demonstrated that the(SiO_(4/2)) units in siloxane resin composition(HSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c) can make it more stableor soluble.

COMPARATIVE EXAMPLES 6 AND 7

Siloxane resin compositions(MeSiO3/2)_(0.49)(PhCH₂CH₂SiO_(3/2))_(0.16)(SiO_(4/2))_(0.35) (Comp.Example 6) and (MeSiO_(3/2))_(0.4)(PhSiO_(3/2))_(0.25)(SiO_(4/2))_(0.35)(Comp. Example 7) were prepared by using the same procedures discussedin Examples 2 and 3 except that the component (B) was changed fromHSiCl₃ to MeSi(OMe)₃ and the weight parts of the components wereadjusted as shown in Table 5.

Thin films were processed from samples Comp. Example 6 and Comp. Example7 using the same procedures discussed in Example 1. The results areshown in Table 6.

Examples 2 and 3 and Comparative Examples 6 and 7 demonstrated that theHSi-based siloxane resin composition(HSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c) can lead to thin filmsthat are more resistant to solvent rinse and have a lower water contactangle than the MeSi-based siloxane resin composition(MeSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c).

TABLE 5 Preparation of samples Comparative Examples 6 and 7. Wt. PartsWt. Parts Wt. Parts Wt. Parts Wt. Parts Example (A) (B) (C) (D) (E) C6100 5.97 5.36 3.54 5.99 C7 100 5.78 6.32 5.61 7.04

TABLE 6 Thin film properties of samples Comparative Examples 6 and 7.Example Th, Å ΔTh, Å WCA, ° C6 1803 224 80.5 C7 2490 1508 80

EXAMPLES 8 AND 9

Siloxane resin compositions,(PhCH₂CH₂SiO_(3/2))_(0.185)(SiO_(04/2))_(0.815) (Example 8) and(PhSiO_(3/2))_(0.21)(SiO_(4/2))_(0.79) (Example 9) were prepared bycombining in a glass container cooled with an ice-water bath components(A) 1-methoxy-2-propanol, (C) tetrachlorosilane, (D) PhCH₂CH₂SiCl₃ orPhSiCl₃ and (E) water according to Table 7. The resulting solutions wereheated under reflux for 20 minutes and stripped in reduced pressureuntil 50% of the total weight remained. Water in an amount of 1.5% oftotal original weight was added and 1-methoxy-2-propanol was added untilthe total weights were identical to the original total weights. Thefinal products were clear solutions.

Thin films were processed from samples 8 and 9 and characterized usingthe same procedures discussed in Example 1. The results were summarizedin Table 8.

Examples 8 and 9 demonstrated that siloxane resin compositions,(PhCH₂CH₂SiO_(3/2))_(0.185)(SiO_(4/2))_(0.815) and(PhSiO_(3/2))_(0.21)(SiO_(4/2))_(0.79) can lead to thin films that areresistant to PGMEA rinse, have a water contact angle between 55 and 75degrees, strongly absorbs 193 nm light, and can be completely removedwith a commercial stripper, Ashland NE-89.

TABLE 7 Preparation of samples Example 8 and Example 9. Wt. Parts Wt.Parts Wt. Parts Wt. Parts Wt. Parts Example (A) (B) (C) (D) (E) 8 100 012.30 3.94 6.71 9 100 0 12.90 4.25 6.25

TABLE 8 Thin film properties of samples Example 8 and Example 9. ExampleTh, Å ΔTh, Å WCA, ° k n Etch rate A/min 8 2059 4 71 0.38 1.68 >2059 92156 8 71 0.39 1.76 >2156

1. A siloxane resin having the formula(HSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c) where R is Z, Z(CH₂)_(n)or ZO(CH₂)_(n) where Z is a phenyl or substituted phenyl group; n has avalue of 1 to 6, a has value of 0.01 to 0.7, b has a value of 0.05 to0.7, c has a value of 0.1 to 0.9 and a+b+c≈1.
 2. The composition asclaimed in claim 1 wherein Z is substituted phenyl group and thesubstitution is selected from HO—, MeO—, CH₃—, CH₃CH₂—, and Cl—.
 3. Thecomposition as claimed in claim 1 wherein a has a value of 0.2 to 0.5; bhas a value of 0.15 to 0.35, c has a value of 0.25 to 0.6, and a+b+c≈1.4. The composition as claimed in claim 1 wherein R is selected from(2-OH)PhCH₂CH₂CH₂CH₂—, PhCH₂CH₂—, and Ph where Ph represents phenyl. 5.A method of making a siloxane resin wherein the method comprises forminga reaction mixture comprising water, HSiX₃, RSiX₃ and SiX₄ and organicsolvent, where X is a hydrolyzable group, R is Z, Z(CH₂)_(n) orZO(CH₂)_(n) Z is a phenyl or substituted phenyl group, and n has a valueof 1 to 6; said method comprising reacting the reaction mixture toproduce the siloxane resin.
 6. The method as claimed in claim 5 whereinthe hydrolyzable group is selected from Cl, Br, CH₃CO₂—, and an alkoxygroup having 1 to 6 carbon atoms.
 7. The method as claimed in claim 5wherein HSiX₃ is selected from HSi(OCH₂CH₃)₃ and HSiCl₃.
 8. The methodas claimed in claim 5 wherein RSiX₃ is selected from PhCH₂CH₂SiCl₃ and2-OH)PhCH₂CH₂CH₂Si(OEt)₃ where Et represents an ethyl group and Phrepresents a phenyl group.
 9. The method as claimed in claim 5 whereinSiX₄ is selected from Si(OCH₂CH₃)₄, and SiCl₄.
 10. The method as claimedin claim 5 wherein there is 1 to 70 mole % HSiX₃; 5 to 70 mole % RSiX₃,and 10 to 90 mole %, % SiX₄ with the provision that the amount of HSiX₃,RSiX₃ and SiX₄ is approximately 100 mole % based on the total moles ofHSiX₃, RSiX₃ and SiX₄.
 11. The method as claimed in claim 5 where wateris present in the amount of 0.5 to 3 moles water per mole of X groups inthe silane reactants.
 12. The method as claimed in claim 10 whereinthere is 20 to 50 mole % HSiX₃, 15 to 35 mole % RSiX₃, and 25 to 60 mole% SiX₄.
 13. The method as claimed in claim 11 wherein the water ispresent in an amount of 0.5 to 1.5 moles per mole of X groups in thesilane reactants.
 14. The method as claimed in claim 5 wherein thesolvent is selected from THF, ethanol, propanol, 1-methoxy-2-propanol,2-ethoxyethanol, MIBK, propylene methyl ether acetate and cyclohexanone.15. The method as claimed in claim 5 wherein the solvent is present inan amount of 70 to 99 wt % based on the total weight of reactionmixture.
 16. The method as claimed in claim 5 where there isadditionally a catalyst present in the reaction mixture.
 17. The methodas claimed in claim 16 wherein the catalyst is HCl.
 18. The method asclaimed in claim 5 wherein the reaction is carried out for an extendedperiod of time with heating from 40° C. up to reflux temperature toincrease the molecular weight of the siloxane resin.
 19. Ananti-reflective coating composition comprising (A) a siloxane resinhaving the formula (HSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c) whereR is Z, Z(CH₂)_(n) or ZO(CH₂)_(n) where Z is a phenyl or substitutedphenyl group; n has a value of 1 to 6, a has value of 0.01 to 0.7, b hasa value of 0.05 to 0.7, c has a value of 0.1 to 0.9 and a+b+c≈1; and (B)a solvent.
 20. (canceled)
 21. The anti-reflective coating composition asclaimed in claim 19 wherein there is additionally present up to 5 wt %water based on the total weight of the composition.
 22. Theanti-reflective coating composition as claimed in claim 19 where thereis additionally present a cure catalyst.
 23. (canceled)
 24. A method forpreparing an anti-reflective coating on a substrate, said methodcomprising (I) applying an anti-reflective coating composition onto asubstrate to form a coated substrate, wherein the anti-reflectivecoating composition comprises (A) a siloxane resin having the formulasiloxane resin having the formula(HSiO_(3/2))_(a)(RSiO_(3/2))_(b)(SiO_(4/2))_(c) where R is Z, Z(CH₂)_(n)or ZO(CH₂)_(n) where Z is a phenyl or substituted phenyl group; n has avalue of 1 to 6, a has value of 0.01 to 0.7, b has a value of 0.05 to0.7, c has a value of 0.1 to 0.9 and a+b+c≈1, and (B) a solvent; and(II) curing the coated substrate, to form the anti-reflective coating onthe substrate.
 25. The method as claimed in claim 24 wherein thesubstrate is a semiconductor device.
 26. The method as claimed in claim24 wherein the anti-reflective coating composition is applied by spincoating.
 27. The method as claimed in claim 24 wherein the coatedsubstrate is cured by heating at a temperature in the range of 80° C. to450° C.
 28. The method as claimed in claim 24 wherein the coatedsubstrate is cured by heating at a temperature in the range of 150° C.to 225° C.
 29. The method as claimed in claim 24 wherein the coatedsubstrate is cured under an inert atmosphere.
 30. An anti-reflectivecoating on a substrate produced by the method as claimed in claim 24.31. The method as claimed in claim 33 wherein the cure catalyst isselected from sulfuric acid (H₂SO₄), (4-Methylthiophenyl)methyl phenylsulfonium triflate and 2-Naphthyl diphenylsulfonium triflate.
 32. Themethod as claimed in claim 24 wherein the solvent is selected from1-methoxy-2-propanol, propylene methyl ether acetate and cyclohexanone.33. The method as claimed in claim 24 where there is additionallypresent a cure catalyst selected from inorganic acids, photoacidgenerators and thermal acid generators.